Telephone system.



F. W. DUNBAR.

TELEPHONE SYSTEM.

APPLICATION FILED Nov. 12. 1904.

Patented 15111.9, 1917.

3 SHEETS-SHEET I.

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FIW. DUNBAR.

TELEPHONE SYSTEM.

' APPLICATION FILED NOV-I21 1904- 1,?31 1 68a, v Patented Jan. 9,1917.

3 SHEET$SHEET 2.

F..W. DUNBAR.

TELEPHONE SYSTEM. APPLICATION FlL ED NOV- IZ, I904.

PatentedJan.9,1917.

3 SHEETS-SHEET 3 KEQZN @223: $3313 0000 o EWN w a part of "this specification.

OFFIQE.

AEGIS W. DUNBAB, OF CHICAGO, ILLINOIS, ASSIGNOR, BY MESNE ASSIGNMENTS TO KELLOGG SWITCHBOiflRD @5 SUPPLY COMPANY. A CORPORATION OF ILLINOIS.

TELEPHONE SYSTEM.

Specification of Letters Patent.

Patented Jan. 9, 191?.

Application filed November 12, 1964. Serial No. 232,440.

.cise,'and exact description, reference being had to the ac'c'ompanymg drawings, forming My invention ralates to telephony, and has for its object the provisionof an. imiv proved telephone exchange system wherein advantages of automatically and manually controlled line connectors are present and disadwantages in these classes of apparatus are eliminated. Broadly speaking, Iobtain these results by making these line connectors (which, in the preferred embodiment of my invention, are cord circuits) par-, tially under automatic control and partially under manual control. The end of each. cord circuit that is placed under automatic control is the answering end.- Traveling switching mechanism is employed for selectively eifecting connection between the answering ends of idle cord circuits and calling telephone lines. The present invention finds its embodi merit in a pair of moving line terminals for each telephone line and motor mechanism jointly controlled by the cord connecting apparatus and a subscribers apparatus for efecting'engagement between these terminals and the terminals of an idle cord circuit, that may be brought into engagement with the said line terminals by the movement of the latter. This motor mechanism is desirably not constantly operated, but is preferably only operated onthe initiation of a call, to which end I associate the operating winding of each mechanism with the line in such a way that when the line circuit is operativcly inetallically closed at a subscrihens station. the circuit through the said winding will be complete and the motor mechanism set into operation. The contiiiuity of this circuit. including the winding, not only depends upon the subscribers switch-hook, but also upon circuit connections at the exchange controlled by the cord connectors. The presence of some one of these circuit connections is necessary to the completion of the circuit through the winding, and such circuit connections are always placed in position to be included in circuit with the winding by the apparatus of the cord circuitsiwhen the said cord circuits are busy. This apparatus, when their associate cord circuits are idle, serves to effect removal of these latter circuit connections, which circuit connections-are preferably located altogether at the oilize. .Each switching device operated by this motor winding is provided not only with the line terminals, but

also a terminal of a circuit controlling the winding which rides over terminals of the allies connections spoken of, whereby circuit ismaintaiiied through the winding as long as the said oiilce connections are main tained complete by the apparatus associ-. ated with busy cord circuits, whereby theline'te'rminals are caused to pass over the terminals of the answering ends of the busy cord circuits. lVhen the said terminal of the controlling circuit comes into contact with a terminal of an office connection that is rendered incomplete by the apparatus of an idle cord circuit obviously, the circuit thatcontrols the winding is then open and the movement of the traveling switching mechanism ceases, such cessation occurring with the line terminals of the calling line ,in contact with the terminals of the answering end of the idle cord circuit.

Avery important feature of my invention resides in the adaptation. of my novel, apparatus to telephone lines already equipped in which relays were originally installed for the purpose of operating line signals. I adapt this relay mechanism to the control of the motor winding provided for each line and the circuit that controls said motor winding is, therefore, preferably included in nism that governs the continuity of said controlling local circuit at one point, the balance of the control being'obtained by the traveling terminal of the winding and the/105 oilice connections. whose operative condition is determined by the cord circuits, all as hitherto set forth. In order that special signaling lamps may not be required the traveling switch contacts that have been described are also accompanied by another moving switch contact under the control of the motor winding, which latter contact cooperates with terminals of signaling circuits associated with the cord circuits, so that, when the movement of the traveling switching mechanism is arrested, the circuit through the calling signal will be completed to notify the operator of a new call. The

- opposite end of each cord circuit is provided for application to multiple switch-board systems, it has other applications which will be readily understood to those skilled in the art. Where the invention is employed in connectiofi with multiple switch-board systems the telephone lines may be connected with the different sections of the switchboard in accordance with any suitable practice, as the apparatus of my invention does not interfere in any way with the usual operation and arrangement of the operators listening keys, ringing keys/testing facili 'ties, and the supervision of the called sub: scribers line. Inasmuch as the answering end of each cord circuit ischanged in the manner specified, I have provided supervisory signals for the calling line which are brought into operation by means of another feature of my invention. I do not wish to be limited, however, to the provision of any supervising means, but have employed the same asthey have been found very desirable in modern practice of telephony. In carryout this feature of my invention the same traveling contact or terminal that is em-' ployed .to effectthe operation of a calling signal is also employed to associate the supervisory signal with the calling line. this supervisory signal being limited purely to the functions of a supervisory signal, the functions of a calling signal being apportioned to a particular instrumentality pro Vided in addition to the supervisory signal.

.The circuit relations of the supervisory signal for the calling line that I prefer will be more fully hereinafter set forth.

I have shown in a general way in what manner a calling line will automatically be to the operator that the manually operated brought into connection with the answering end of an idle cord circuit. When tWo connected subscribers are through with their conversation and have replaced their telephones. the supervisory signals will indicate connecting plug should be withdrawn, Whereupon the movable switch is restored, through the agency of electro-magnetic apparatus governed by the cord circuit, to its initial position, so that the calling subscriber may then be at liberty to initiate another call.

Another feature of my invention relates to the distribution of work among the operators, and by this feature of my invention a wide range of flexibility in such distribution is effected, particularly in the case of multiple switch-boards. In multiple switchboard practice it is well understood to those skilled in the art that each line has, in addition to the multiple jacks distributed throughout the boards of the system, an answering jack and a line indicator, the answering jack and indicator of each line being collocated. These indicators and jacks are distributed in groups of uniform quantity among the different sections of the switch-board, so that there is disposed at all operators positions the same number of an swering jacks and the same number of line signals. It is, of course, apparent that telephone operators possess varying degrees of skill and speed in handling calls. The uni-- form distribution of answering jacks and line indicators renders it difficult and impracticable in accordance with present practice to apportion work to suit the capacity of the different operators. The ordinary skilled operator can properly attend to 270 calls in an hour if the calls be uniformly distributed through-the sixty minutes. The averagetime or length of each call is approximately one minute and twenty seconds, thus allowing each cord circuit to complete 45. calls per hour if kept busy throughout the sixty minutes. Six cord circuits kept uniformly busy throughout the hour can," therefore, handle 270 calls during the hour the work of the ordinary operator. Certain operators can, however, handle in a proper manner more than 270 calls per hour, While others, less skilled, are unable to handle properly as many as 270. Moreover, the flexible cords require frequent renewals-and a certain percentage may be continually out of order. For these reasons I provide a greater number of cord circuits at each-operators position than six, say ten. More-' over, I provide means whereby one or more cord circuits at each operators position may be thrown out of operation or out of opera- 'tiv'e relation with respect to the line circuits, whereby each operator may be given as many cord circuits in operative relation to the line circuits'as can be properly hantelephony it is customary to provide an in termediate distributing board whose func- 1 dled by her. Thus certain operators may have but three or four cord circuits in operative condition, while others, highly skilled,-may have eight, nine, or even ten cord circuits placedin operative relation to the calling lines. By this means each operator may be kept as busy as her degree of skill Will permitand paid according to her ability. or skill, the number of cord circuits which she can efiiciently handle being a correct gage or measure of the number of calls- Which she can efliciently handle per hour.

It may be properly assumed that one eighth of thetotal number of calls made during the entiretWenty-fourhours of'the day will occur during the busiest hour. The switch-board must be designed to handle the business at all hours of the day. Consequently the number of sectionsof, switchboard is determined by the number of operators required to handle the business during this busiest hour. If, duringthis busiest hour-01 momenteach operator be employed at her maximum efficiency, the necessary switch-board equipment will be minimum. In the present systems of manual tion is to present facilities for dist "ibuting the answering spring-jacks and calling signals throughout the various sectlons of.

switch-board, so asto cause as uniform a distribution as possible of the/calls during this busiest houror moment. At best, however, owingto the dailyfluctuations in the amount of business from certain groups and from all classes of lines, it is impossible to distribute the said acks and calling signals so as to secure more than rough approximationto a uniform distribution of calls.

means of my invention, however, a distribution of calls may be automatically secured, such that when the number of cord v circuits in operative relation with the calling lines is properly proportioned according to the skill of the lndivldual operators, each operator will be working at her maximum efficiencv not only during the busy hour, but at all hours. Consequently the necessary number of sections of switch-board will be decreased and fewer operators at all hours of the day will be required.

In all present manual systems of telephony the calls at all hours of the day are distributed throughout the entire switchboard, this requlring the presence of one or'more operators at each section of the board at all times save certain of the night hours When the business is so slack that from one to ten operatorsdcpending upon the size of the exchangecan handle the entire number of calls by walkingfromsection to section and picking up the various calls as; they may come in. At all such times the efficiency of the operators-reckoned on a basls of number of calls answered per houris very low, the result being that the average number of calls handled per operator per hour throughout the twenty-four is less than half the number Which the average operator is capable of handling efiiciently were she kept uniformly busy. By means of my invention I am enabled to distribute the calls so that during the night hours all calls will appear at the first section of switch-boardor at the first 'two or threedepending upon the size of the exchange and the volume of night business, so that as the business increases operator after operator may be added as required the dayresulting in a decrease in operating expenses of 50% or more I do not contemplate, however, in large exchanges providing the necessary switching facilities, so that each line may select any one of all the cord circuits, although -in smaller switchboards it would be preferable to do so. in large exchanges I prefer to divide the lines into groups of several hundred each and divide the cord circuits into a corresponding number of groups, so that any line in a certain group may select any cord circuit assigned to that group if the lower numbered cord circuits of that group already be busy, and if that particular one be not busy. For example, I will assume an exchange of 4,500 lines and provide group of twenty-seven cord circuits for each 500 lines, thus making two hundred forty-three cord circuits in all. In addition, I will preferably provide twenty-seven extra cord circuits, one for each operators position, thus making a total of two -hundre seventy cord circuits, divided equally between nine sections of switch-board, or thirty to the sectionand ten to the operator. .Each operators position would normally have one cord circuit belonging to each group of 500 lines and one extra cord circuit to be connected as the business may dictate. Each section would, therefore, be provided with. three cord circuits for each group of 500 lines a and three additional ones.

During the night hours, therefore, all calls would appear at the first section of switch-board, unless in some particular group of 500 lines there were more than three calling lines t 1 simultaneously connected for COI1VelSZtt10l1- I operator only was required for the business at this time, that five-sixths of the total business which this single operator could efficiently handle wasoriginating in a group containing only one-ninth of the total number of lines.

spoken of are, however, provided at this 1 each group; for example, he may cut or rensection of switch-board, so that they may be switched onto any particular group of lines which. are found to originatea large amount of night business, thus allowing six simultaneous calls from the same group of 500 lines appearing at the first section.

In the example above chosen as an illustration I would employ selector switches, each comprising thirty points, that is facilities for connecting thereto thirty cord circuits. Ordinarily the first twenty-seven points of each switch of each group of 500 lines would be connected to the twenty-seven cord circuits assigned to that group, the remaining three points serving for the extra cord circuits arranged and connected as the business of each group might dictate. The first point of each switch would be connected to the cord circuit appearing at the first operators position, the second point being.

connected to the cord circuit appearing at the second operators position, etc. Each section thus has in addition to the so-called extra cord circuits, three cord circuits for eachgroup of 500 lines, it being apparent that the exchange manager may so divide the cord circuits at the various sections and positions as to accommodate their number to the ability of the operators and still preserve a uniform number of operative cord circuits for each group of lines, or a number correctly proportioned to the business of der inoperative the first, second and third cords of one operator, the fourth, fifth and sixth of a second operator, and the seventh, eighth and ninth of a third operator, thus giving each of these three operators six effective or operative cord circuits, and diminishing the number of cord circuits of each group of 500 lines by one each. It will be apparent to those skilled in the art that an unlimited number of combinations may be thus secured and the business of each operator adjusted to meet her abilities. Moreover, as thirty cord circuits are provided for each group of 500 lines, each, if worked to its "maximum efliciency, will be capable of handling 15 calls per hour, or a total of 1,350 calls during the busy hour, representing an average of 27 calls per subscriber The extra cord circuits-above handling a greater number of calls per day than will originate in an average exchange of the size chosen as an example.

My invention contemplates means associated with the selective switches for rendering impotent those cord circuits at each or any operators positions which it may be desired tocut out of service, so that the selective switches will pass by those circuits thus rendered impotent as though they were already in use.

I will explain my invention more fully by reference to the accompanying drawings in,

which Figure 1 represents the adaptation of my invention to one well recognized system of telephony. Fig. 2 represents the adaptation of my invention to another well recognized system of telephony. Fig. 8 is a diagrammatic view illustrating the distribution that may be made of the lines and cord circuits, the apparatus of the invention enabling a wide range of distribution to suit the business of the exchange and the capacity of the operators.

Like parts are indicated by similar characters of reference throughout the different figures.

, Referring first more particularly to Fig. 1, each subscribers station, A, B, O, is pro- .vided with customary common battery subscribers apparatus, the switch-hook at each station serving operatively metallically to unite the sides of the line when the receiver is removed.

I do not deem a detailed description of the 4 subscribers station apparatus to be essential, as the illustration is sufficient to make the sameunderstood to those skilled in the art. Stations B and C in'Fig. 1 are party line stations.

Although I have illustrated one arrangement of subscribers station apparatus, it will be obvious to those skilled in the art that other arrangements may be employed at the sub-stations, and I do not wish to be limited to the arrangement and apparatus shown, nor do I wish to be limited in all embodiments of the invention to its application to a common battery system. V

The subscribers lines indicated are metallic lines and extend in two branches to the exchange, where they terminate in the armatures 11 of a cut-off relay2. The alternate contacts of the armatures, those contacts that are engaged by the armatures when the cut-off relay is energized, consti- *tute terminals of the office end of the' line The system illustrated being a multiple switch-board system, there are also provided upon othersections of the board than where jack 3'is located other jacks 1in connection with the said alternate contacts and the 'oiiice endof the line similar to the connection of jack 3. That which in a multiple switchboard would correspond to an answering jack and in any otheFswitch-board would correspond to a line-jack, is found in the terminals 5-6 which are normally connected with the .subscribers line through the agency of the normal contacts of the armatures 78 of a relay 9. The terminals 5-6 are normally in the position indicated at the right-hand of the figure in readiness to be connected with an idle cord circuit. In the figure beingparticularly described there is illustrated one set of tip contact buttons 7 and one set of sleeve contact buttons 8 normally out of operative relation with the terminals 5 41 These contact buttons 7-8 correspond to the tip and sleeve of the answering plug hitherto used in manually operated boards, the connecting plug 9 being of any preferred type and adapted for insertion within the jacks 3-4. There are as many rows (horizontal rows being in dicated in a straight line, though the.arrangement of the rows in any given direction or position is not essential to the prac tice. of the invention) as there are telephone lines to which a group of cord circuits has been assigned. The tip and sleeve terminals 78 of one row aremultipled with those in theadjacentrows, so that any pair of termina-ls '5 6 may ride over any row of tip nd sleeve contacttbuttons and rest in engagementwith thoseco-ntact buttons that are connected with an idle cord circuit. There are as many multipled sets of sleeve contact buttons and tip contact buttons as there are cord circuits assigned to a group of lines and in some cases more in order that the additional-buttons may be provided with their cord circuits for reserve, as will be herein after set forth. In the left of Fig. 1 the line terminals 56 have been shown shifted into connection with sleeve and tip contact buttons, whereby a calhng line,subscr1ber-A, is

connected with the strands of .a cord circuit whose connecting plug 9 is placed in a lineack ofa called subscriber, as B orC. Normally however, these terminals 5 6 are not in connection" with any sleeve and tip contact button, as they require the agency of a selecting magnet or motor 10 to place them in the relation illustrated at the lei't'of the drawing. The controlling circuit of the winding of theniotor 10 is referably not a winding but is one thatincludcsthe common battery 11. the magnet or relay 9, which magnet is of high resistance, the alternate contact of armature switch 12, the said armatureswitch,

grounded battery 11. winding 10 is thereupon attracted to move t h s for engaging the said contact 14 and any of the companion contact buttons 16 arranged in the same row,'the number of contact buttons 16 equalling the number of tip contact buttons and equalling also the number of, sleeve contact buttons, obviously. The projection 15 is so wide that it makes connection with one button in its path before leaving another. The controlling circuit thus outlined is normally open at the switcharm 12, so that the controlling circuit is normally ineiiective. When a subscriber initiates a call the circuit is metallically closed at his s tation by the switclrhool; thereat, wiereupon current finds path from the. battery 11 through the winding 0% magnet or line relay 17 to the normalcontact or" the lower cutoti relay armature 1, over the subscribers line, to the normal contact of the upper armature 11, the relay 1? thereupon being energized to attractits armature mechanically coupled with the switch arm 12, thereby closing the then only existing gap in-the controlling circuit. As there is included the winding of relay 9 in this controlling circuit, the grounded contact of said relay is then engaged by its armature, whereby circuit is closed through the winding 10, that'may be tracedfrom the said grounded contact of the relay 9, to the front contact of the armature of relay 17, to the bifurcated lazy arm 18, the contact for said arm with which said arm is normally held in engagement by the spring 19, the said winding 10, to the the contacts or terminals 6, 5 and 13, which are preferably arranged in straight line in a single bar, mechanically speaking, against the force of an expansion spring 20, thesaid bar being notched at 21, so that each operation thereof by the armature will effect a movement of the-contacts 5, G and 13 a distance equal to the distance between the centers of adjacent buttons 7, between the centers of adjacent buttons 8, and between the centers of adjacent buttons 1416. The dc tent 22 looks the bar in the position to which it has been advanced against the force of the spring 20. After each attraction of the armature of the relay 10, the lazy arm 18 is moved away from its contact and stays away until the armature has been released, which operation is secured. because the free end of said lazy arm is bifurcated, an extension of said armature being interposed between the bifurcated members of the arm, it being the armature extension alone that has operating influence upon said arm.

The armature of the I When the armature is released, it will 13o again be attracted if the button 16 with which the extension has now been placed in engagement happens'to be grounded, it

- sertion of the connecting plug 9, so that the controlling circuit of the winding 10 that included the high resistance magnet 9 is opened, the armature of said magnet falling away from the grounded contact, thereby opening the circuit containing the winding 10, so that the selecting switch is no longer to be operated by the armature of the magnet 10, whereby the line terminals 5-6 are engaged with buttons 8.7 that are the terminals of the idle cord circuit with which the button .16 then in engagement with the element or brush 15 is associated. When a calling line and its selecting mechanism have sought out an idle cord circuit, the brush 15 and the engaging contact 16 effect the calling signal to the operator as will be hereinafter set forth. It is understood that each row of buttonshas associated therewith a motor operated switching device including contacts 5, 6 and 13, and that the contacts 16 that the brush 15 engages are grounded when their cord circuits are busy. The form of motor mechanism illustrated may be departed from and it is understood that other means for securing an interruption of the motor winding circuit, where the operation of the motor is thus controlled, may be departed from and equivalent apparatus well known to those skilled in the art employed. As hitherto stated, the first contact button 16 encountered by the brush 15 has been grounded because its cord circuit is supposed to be busy, such ground being indicated by dotted lines at 24. It will be seen that not only are the tip and sleeve contact buttons 78 of the various cord circuits of a group multipled together respectively, but that the associate buttons 16, equal in number to the said group of cord circuits, are also multipled, one multipled group belonging to one cord circuit, another multipled group belonging to another cord circuit, and so on,- just as in the case of each group of multipled tip contact buttons and multipled sleeve contact buttons, so that any wiper 15 belonging to any motor mechanism, when encountering any contact button 16 in its row that may be grounded, is caused by the mechanism to pass beyond said contact.

Apparatus whereby a ground is placed upon a group of multipled contact buttons '16 belonging to one busy cord circuit is illustrated in detail, this group being the second group from the right of the mechanism shown at the lower left hand corner of Fig. l and the continuation of this group in the second row from the left of the corresponding buttons upon the lower right hand corner of Fig. 1. The groups of the "arious buttons 7, 8 and 16 upon the right of the drawing .are virtually continuations of the slmilarly numbered buttons upon the left of in the second row from the right in the left hand corner of the figure and the second row from the left in the lower right hand corner of the figure, there is provided for each cord circuit such a conductor as that indicated at 25 that desirably includes an armature 26, the said armatures normal contact, the normal or back contact of the armature 27, which contact is connected with the armature 26, the front or alternate contact of the armature 28, which contact is connected with the armature 27 and the grounded battery 11. When a cord circuit is idle, the conductor 25 is open, because of the unattracted armature 28, as will be fully set forth. The conductor 25 is grounded, together with the contacts 16 connected therewith, by the switch 12 when it is released by the line-relay, such grounded connection being traced from the grounded terminal of the relay 44, to the switch 12, the contact terminal 13, and to the row of contact buttons 16 in, electrical connection therewith,

so that the Wiper 15 of any selecting mechanism making contact with any other button 16 in the group connected with the conductor 25, will be movedfrom the button 16 thus engaged by means of the motor 10 and the associate mechanism that has been specified.

When the cordcircuit has been selected, and the cut-off relay has attracted its. armatures 1, circuit through the winding ofmagnet or relay 29 associated with the armature 28 is closed, which' circuit may be traced from the grounded battery 11, to the sald magnet winding, the connection of said winding with the sleeve strand of the plug- 9, the group of buttons 8, the wiper 5 connected with one of said buttons, the terminal 5, the armature '8', to the grounded terminal of the cut-off magnet 2, whereby the relay winding 29 battery 11, in addition to energizing the winding of cut-ofi relay 2, has its current is energized. The

the switch element 7 divided ust before it reaches the said relay,

is supplied with battery current and the said relay is caused to attract both of its armatures, the armature 26. thereupon connecting the call signal 3%, preferably a lamp, in circuit with the common battery-11 by way of the armature 26 and its front contact, the armature 27 and its back contact, the armature 28 and its front contact, and

.the connections illustrated between said armature28 and the battery. The operator in response tothe signal conveyed by the lamp 32, 'upon depressing her listening keys 33 and having ascertained the line to be called, selects the wanted subscriber by operating a ringing key. In the instance shown, she operates the ringing key ,3 l-34 to signal one of the sub-stations on the party line and the key 35-351to signal the other station, though the adaptation of the invention to party line practice set forth is merely to illustrate the wide range of application of the invention, and I do not, therefore, deem a further description of the. operators listening and ringing outfits to be essential, as such apparatus is well understood to those skilled-in the art. When the called line is connected with the connecting end of the cord circuit, supervisory apparatus corresponding with that end of the cord circuit and disposed to the right of the condensers 33'33, has its operative condition changed. This supervisory apparatus is of a type well understood by those skilled in the art and need not be described any further than to state that the supervising relay 34: has added thereto the armature 27, so

sertion of the connecting plug in a manner well understood, and as will be readily understood by reference to the diagram), the said armature 27 is attracted to open the circuit including the signaling lamp 32, the signal of the calling subscriber being thus automatically effaced. The relays E29 and 30 efiectcontrol of the supervisory signal 35 corresponding to the calling subscriber in a way similarto the control of the supervisory signal 36 effected by the relays 37, 34: that correspond in their supervisory control with the relays 30'-29, respectively.

After the calling subscriber has been placed in connection with a called subscriber and still has his telephone from its hook, the magnet 30 still is energized to keep withdrawn its armature38 from its normal back and grounded contact, wherebythe circuit that, when said .relay 34L'is energized (as it is upon the inthrough the lamp 35 remains opened at this point. When said subscriber restores his telephone, the magnet 30 has its circuit opened at the switch-hook of said subscriber, permitting the armature 38 to engage its contact and close circuit through lamp 35, which may be traced from the ground thrown upon said armature 38, the front contact of the armature 39 of relay 29, and

thence to the grounded battery 11, this cir- 5 cuit not being interrupted at the armature 39 because'thewinding of the relay 29 is still included in a circuit that includes the battery 11, a portion of the sleeve strand, a contact button 8 in engagement with the wiper 5, the line. terminal 5, and the ground .at the cu -off relay. Nhen, however, the

brush 5 is moved to its initial position upon the release and restoration of the selective switching mechanism, the winding 29 is deenergized and the signal atis efiaced. The pilot signal controlling relay l0 govern inga pilot signal; 41, may be included in the same'circuit with the signal 35, so that the signal 41 may correspond in its operation to the signal 35. In order that better supervision may bev had a second pilot signal controlling magnet 42 is included-in the circuit in which. the signal 32 is contained, so that the added pilot signal 43, preferably a lamp, may correspond, in its operation to the lamp 32. l believeit to beinvenmion with me tosupply the supervising signaling mechanism associated with the answering end of the cord circuit, in c'ombinationwith apparatus wherebya connection between the terminals of the answering-end of the cord circuit and the terminals of a calling line may be connected automatically.

the rectilineal motion thereof. Such mechanism being illustrated and preferably em ployed, I will describe not only the manner in which the motor may be placed in condition to be'operated, but also the mechanism by which the restoration of the reciprocating mechanism to its initial position maybe efiected.

A releasing circuit is desirably employed which includes an electro-magnet it that controls thedetent22, this magnetlreferring particularly to the left of Fig. 1) controlling the said detent to cause the same to be withdrawn from the tooth upon the bar I .magnet 44 merely the hooks 45 and 30 section 21 with which it is engaged to permit the coil spring 20 to thrust the contacts 5, 6 and 13 to their initial positions.

hen the line relay 1'?' has released the switch arm 12 upon the selection of a cord circuit by the line, the releasing circuit con taining the magnet 44 is partially closed. hen the connecting plug 9 is withdrawn after a conversation and subscriber A has restored his telephone receiver, the complete releasing magnet circuit is then established,

which circuit may be traced from the grounded terminal of the winding of magnet '44, the switch arm 12, the terminal 13, the buttons 16 in electrical connection therewith, the conductor 25, the armature 26 and its normal or back contact, the armature 27 and its back contact, the armature 28 and its front contact, to the grounded battery 11. The armature of the magnet 44! is pivoted between its ends and is provided with a spring catch or hook 45 that is adapted to engage with the hook 46 upon the detent 22 which is pivoted between its ends, the said detent having a spring at one end to force the other end into engagement with a tooth upon the bar 21. The energization .of the effects connection between 46, whereby said detent, which is grounded, effects the completion of a circuit which may be traced from the grounded detent 22, to the hook 45, the relay 9, to the grounded battery 11, the said relay being thereby energized to move the switches 7 and 8 from their contacts and disconnect the cord circuit from the calling subscribefs line, whereby the cut-off relay 2 is deenergized to restore its armatures, and the relay 29 is included in open circuit to efl'ace. the signal occasioned at the lamp 35. The circuit including the releasing magnet 44 is brokenwhen the magnet 29 is included in open circuit, the opening in the circuit occurring at 28, whereby the relay 44 is de'energized, permitting the spring 47 to pull the detent out of engagement with the bar section 21, so that the spring 20 may restore the switching apparatus. The hooks '4546 are separated by the projection 48 that engages the spring hook 45 when the restoration has been nearly completed,

thereby restoring the selecting switching mechanism to its initial idle condition. The

contact between springs 45 and 46 closes a circuit through the relay 9 which relay upon energizing, disconnects the line wipers from the subscribers line during the restoration of the switch. Thus it will be seen that by the removal of. the armature 28 from its front contact, the ground is removed from the series of contacts 16 in electrical connection with the brush 15, so that any brush similar to 15 thereafter coming into contact with any of these contact buttons will not cause a continuation of the operation of the selected groups of contacts 16 to motor mechanism, but said motor mechanism will thereupon be arrested as has been explained.

The energization of the releasing magnet cannot take place until after the calling subscriber has restored his telephone receiver, for the circuit of said magnet depends upon the contact between the armature 26 and its normal orback contact, which cannot be had, in preferred practice, until the calling subscriber has restored his receiver and effaced the signal furnished by the indicator 32, as heretofore specified, although the magnet 44, while in readiness to be effective, is not effective until the operator has Withdrawn the connecting plug in order to deenergize the magnet 34 to permit the closure of the armature 27 against its back contact. As soon, torhas inserted a leasing magnet is is jointly scribers (in shown, the calling subscriber) and the apparatus of the operator. Prior to the insertion of the connecting plug, however, it is obvious that the calling subscriber has full control over the releasing magnet and may restore the switching mechanism associated therewith at any time before the connecting plug is inserted by restoring his telephone on its switch-hook.

The magnet 9 is desirably placed in series with the releasing magnet 44 associated With a busy cord circuit. The latter magnet is, therefore, preferably wound to a low resistance, while the magnet 9 is wound to a higher resistance, whereby the magnet 44 is prevented from operation when placed in series with the magnet 9, but the latter magnet is permitted to operate. When the magnet 44 is to operate, it encounters the low resistance path from the armature 28 to the battery, the magnet 42 being desirably of low resistance.

If any operator should be provided With so many cords, as to be beyond her capacity during the busiest time, I provide means whereby some of her cords may be cut out of service, so that selecting switches passing over a group of contacts will not select more than a predetermined number of idle cord circuits. In this way the work that an operator has to do isaccurately adjusted to her maximum capacity. The means whereby the cord circuits are made unresponsive to a calling line resides in imposing upon each group of contacts 16 associated with a cord circuit to be elided, an artificial .condition which, in the embodiment of the invention shown, should be an artificial ground that may be placed thereupon by the manually operated switches 47 that may be thrown into and out of electrical connection with the accomplish connecting plug, the rebeyond line control but controlled by one of the subtherefore, as the operathe embodiment of the invention the equipment narrates the purpose desired. In addition to providing instrumentalities whereby the amount of work assigned to an'operator may be reced to meet her capacity, I also provide whereby the work of ors may be increased, which feature forth in connection cc more fully set u an Fig. 3, after a slight 2 has heen given.

Fig. 2 indicates what is known as a three wire cord circuit, for use in multiple switchboard practic in which line and cut-off relays are employed. The third cord strand (4 is connected with a third contact element 1 the connecting plug and has separable connection-with the conductor a normally in engagement with the moving member d, con trolled by the relay 9 which controls also the elements 7 -8 The switch d is a terminal of a conductor including the winding of the cut-oli relay 2. Inasmuch as the conductor and the conductor a are added to generally described in connection with Fig. 1, there is added the travcling terminal 13 moving with the terminals G and multipled rows of contact buttons 16, with which the terminal 13 is adapted for electrical connection. The roup of terminal buttons 16 that belongs to a cord circuit is placed in connection with the extra strand a. When the traveling switch rests with the terminal 13' in connection with one of these groups of contacts 16 and the relay 9 that corresponds in function to relay 9 of Fig. 1 is deenergized, the cut-off relay 2, tion to the cut-off relay 2 of Fig. 1, attracts its armature, as the winding of said cut-oll' relay is thereupon included in circuit with the grounded battery 11, whereby the line relay 17, corresponding in function to the line relay 17, is excluded from cir-' It will. be unnecessary further specifidescribe the cord circuit apparatus of Fig. 2, it being sufficient to state that the elements 27', 28", 29', 30', 34, and 42' have functions corresponding to elements 27. 28, 29,30, 3 .,40 and &2.

I have stated how an operator may have her equipment reduced to suit her capacity if it be below the maximum. T will describe with reference to Fig. 3 how the work may be distributed among the diiierent operators positions, the work of which operators may be varied to suit by controlling the operativeness of their cord circuits as hitherto specified.

In Fig. 3 I have not had room to illustrate to the fullest extent the example set forth in the introduction to this specification, but the diagram that is furnished will readily demonstrate the feature of the invention now being described. At each operators position there are indicated nine connecting plugs c, more or less of which are in service, accordcuit. cally to more eliicient description of Fig.

that corresponds in func their maximum capacities ing to the capacity of the operator, there being supplied in addition to each group of nine plugs, an extra plug f, making ten in all. Single lines 9 extend to these plugs, each ofwhich is intended to indicate the group of cord strands leading-to saidplugs. Those plugs, as stated, that are not to be placed in operation have their conditions artificially changed to make them correspond with plugs that are already in use, so that the cords connected with these plugs will not be automatically selected. There are illustrated three divisions, T, H and III, of subscribers lines arranged in accordance with the plan outlined hitherto, there being indicated for each group of subscribers lines two rows,*h i, of 500 rows of contacts, there being thirty groups of contacts in each row. intended to represent all of the multiple contacts associated with a given connecting plug. For example, the connected circles is (there being 500 of such circles corresponding to each plug) represent the tip and sleeve contact buttons 7 and 8 and any additional contact buttons, as the buttons 16, that may be associated therewith. The circles Z indicate the motor mechanism and the associated contacts 13, 5 and 6, forexample, which ride over the sets of buttons 10-40 until a set is found that is associated with an idle plug or a plug whose circuit has not been caused to havethe busy plug. There are 500 such devices Z 1n association with groups I, II and TH of telehonelincs, one for each row, It, i, etc.,-inorder that the calls may be received in the order of: the operators, so that no operator at one section need have any callsto attend to unless the operators at the sections ahead of her have all of their cord circuits in use (considering now the normal business of the exchange).

The first lot of 500 contacts is (shown at the right of group No. I is connected with the first plug at the first position of the first characteristics of a The connected circles is, are

section of-the board. The second lot of such I sets of contacts is at divisionNo. it is connected with the first plug at the second position of the first section of the board. The third lot of contacts 70 is connected with the first plug at the third position of the first section of the board.

The first lot of 500 contacts is (shown at the right of. group No. IT) is connected with the second plug at the first position of the first section of the board. The second lot of contacts 70 is connected with the second plug at the second positionof the first section of the board. The third lot is connected with the second plug at the third position of the first section of the board.

The first lot of 500 contacts 70 of group No. HT is connected with the third plug at the first position of the first section of the board. The second lot is connected with the third plug at the second position of the first section of the board. The third lot is connected with the third plug at the third position of the first section of the board.

If more than nine calls are received from divisions I, II and III at a time, the selectors Z will pass by the contacts associated with the plugs that I have mentioned at section 1 of the board and will seek contacts that are not connected with a busy cord circuit, which contacts will be found in association with the plugs at section N o. 2, if these plugs are not'busy, but if the plugs are busy atsection No. 2, the selectors will'continue in their travel to seek contacts associated with the idle plugs at section No. 3. In order that this result may be accomplished, the fourth lot of 500 contacts at division No. I is connected with the first plug at the first position of the second section of the board. The fifth lot of contacts is is connected with the first plug at the second position of the second section of the board. The sixth lot of contacts 7c is-connected with the first plug at the third position of the second section of the board.

1 The fourth lot of contacts In of group N 0. II is connected with the second plug at the first position-of the second section of the board. The fifth lot of contacts 7c is connected with the second plug at the second position of the second section of the board. The sixth lot of contacts 70 is connected with the second plug at the third position of the second section of the board.

It will be unnecessary to further trace the different connections, as they will be apparcut by an inspection of the diagram. In this way cord conductors extending from the selective switching devices corresponding to each group of subscribers are subdivided into a plurality of groups that are extended to connecting plugs at different sections of the board, the first group of cords being preferably assigned to the first board section, the second group to the second section, the third group to the third section, and so on. At this point it is well to state that I do not wish to be' limited, in practising this feature of my invention, to the traveling selecting terminals of the calling lines, as I desire to claim broadly the arrangement shown in Fig. 3 including any automatically operated means associated in any suitable way, for connecting idle cord circuits with calling lines.

The groups of cords corresponding to each group of lines are connected with the board sections in the same ordei in which automatic selection is effected between the calling lines and the cord circuits. That is, in the example shown, the first group of three cords of the group of lines I is extended to the first board section, the second group to 1,21 1 ,ese

the second board section, the third group to the third board section, and so on. And so with the groups of cords extending from the division II of the lines; the first group of three cords is extended to the first board section, the second group to the second section, and so on. Thus each group of telephone lines has a group of cords extending to each of the board sections, the. group extending to the first board section being first adapted for automatic connection with calling lines, encountered by the traveling terminals of the calling lines, the operators at the second board section, therefore, having no work till the first operators have reached their capacities, the operators at the third board section having no work till the operators at the second board section are fully occupied, and so on. It will have also been observed that the cords of each group are distributed among the various operators positions at the section to which said cords extend, to equalize the work of the operators at each section as far as possible.

While I have provided means whereby the facilities for connecting subscribers at any board section may be reduced to be commensurate with the capacity of less efiicient operators all as hitherto set forth, I have also provided means whereby facilities for putting up connections at the different board sections may be increased or provided to replace broken cord sets. In practising this feature of my invention, one extra plug 7 may be supplied at each operators posit'on, that is, three to a section, and each group of lines has included in the rows of contacts IL- three groups of contacts 0 adapted for connection with said plugs f,- for which purpose a distributing board ,1), or its equivalent, may be provided to which fractions of cord strands extend from the elements 0 and from which what are adapted to constitute the balance of said strands extend to the plugs f. At the board 39 the cord sections may be united as desired, to increase the capacity of any board section, or to replace broken down cord circuits.

In the system of my invention'thereneed .as their contact buttons are the first to be not be any intermediate distributing boards, A

the main distributing board being, however, preferably maintained.

While the different switch-board sections are arranged in serial order, it is obvious that my invention does not depend upon the physical disposition of the sections relative to each other.

There are certain features of my invention that need not be limited to selective switching mechanism having traveling line contacts, and I have claimed said features broadly herein.

It will be obvious that my invention lends itself to a variety of arrangements, associaarness s tions and groupings of cord circuits to suit differing practices, and I do not, therefore, wish tolimit myself to the precise grouping and arrangement shown, nor to the application thereof to multiple switch-boards.

I do not wish to be limited. to a resetting of the moving switch contacts of the selective mechanism to their normal or initial positions by reciprocal movement thereof.

It is obvious that -many changes may be made in the embodiments of my invention herein shown and particularly described without departing from the spirit of the invention, and I do not, therefore, wish to be limited to the embodiments of the invent-ion herein shown, but

Having thus described my invention, I claim as new and desire to secure by Letters- Patent the following 1. A telephone system including a pair of connected telephone lines, a selective switch and a manual link circuit through which a conversational circuit extends, multiple private or test contacts for said selective switch for preventing intrusion upon the talking circuit, means including a relay of said link circuit for altering the electrical condition of said contact to restore to normal said selective switch, and a centralized source of current for operating and talking purposes.

2'. A telephone system including telephone lines, relatively movable switch contacts and an operators link circuit through which a talking circuit between a calling and a called line may be completed, means including a test contact for determining the talking circuit, means for restoring said switch contacts to normal including said test contact and a switch contact in said link circuit, and a centralized source of current for operating and talking purposes.

4 3. A telephone system including -a telephone line, a selective switch at the exchange connected with said line, a manual link circuit connected with said switch, contacts' of said switch and said link circuit forming part of the talking circuit, an additional contact piece for said switch in connection with a contact piece of said link circuit serving to protect the talking circuit against intrusion, means for altering the electrical condition of said contact piece when disconnection is desired, release mechanism for said switch responsive to said altered electrical condition, and a centralized source of current for operating and talking purposes.

4. A telephone system including a pair of connected telephone lines, a selective switch and a manual link circuit through which a conversational circuit extends, a test contact for said switch for preventing intrusion upon the conversational circuit, release mechanism for said switch, means including said release mechanism, said test contact and a relay of said manual link circuit for restoring to normal the said automatic switch,

and a centralized source of current for operating and talking purposes.

5. In a telephone system, a subscribers line, a. switch individual to said line" provided with pair of line wipers and with atest wiper, a plurality of manual trunks one end or" each of said trunks terminating in the banks of said switch, the other end of said trunks terminating in terminal plugs, means with contacts terminating in the bank of said automatic switch, means for operating said switch to automatically select an idle one of said link circuits, a release circuit for said switch including said test contact and apparatus of said selected link circuit, and restoring means in said switch responsive to the closure of said release circuit, and a centralized source of current for operating and talking purposes.

7. In a telephone system a subscribers line, a step-by-step switch individual thereto provided with line wipers and with a test wiper, an operators trunk line, one end terminating in a connecting plug and the other end terminating in bank contacts of said switch, means for operating said switch to connect with said trunk line, means for releasing said switch from said trunk line including a release circuit extending through the said test wiper, and a centralized source of current-for operating and talking purposes.

8. In a telephone system, a calling subscribers line, a switch individual thereto provided with a pair of line contacts and a test contact, a plurality of operators trunk lines, means including said test contact for selecting an idle one of said operators trunks, means for releasing said individual switch including a release circuit extending through said test contact, and a. centralized source of current for operating and talking purposes.

9. A telephone exchange system including a plurality of telephone lines provided with jacks and divided into groups, a plurality of link circuits for each group of telephone lines also divided into groups and extending to link connecting plugs at different sections of the switch-board, automatically operated selective switching mechanism associated with the telephone lines and the answering tnds of the link circuits for connecting said link circuits .with calling lines, and apparatus for changing the electrical character of the link circuits to cause them, when idle, to cooperate with the selective switching mechanism as if they were busy, to enable the said mechanism to pass the same into cooperation with an idle link circuit that may be used, substantiall as described.

10. A telephone exchange system including a plurality of telephone lines provided with jacks and divided into groups, a plurality of cord circuits for each group of telephone lines also divided into groups and extending to cord connecting plugs at different sections of the switch-board, the connecting plugs of each group being distributed among the operators positions at each section, automatically operated selective switching mechanism associated with the telephone lines and the answering ends of the cord circuits for connecting said cord circuits with calling lines, and apparatus for changing the electrical character of the cord circuits to cause them, when idle, to cooperate with the selective switching mecha nism as if they were busy, to enable the said mechanism to pass the same into cooperation with'an idle cord circuit that may be used, substantially as described.

11. A telephone exchange system including a plurality of telephone lines provided with jacks and divided into groups, a plurality of cord circuits for each group of telephone lines also divided into groups and extending to cord connecting plugs at differ ent sections of the switch-board, automatically operated selective switching mechanism, including traveling line terminals and multipled cord contacts engaged by said terminals, said switching associated with the telephone lines and the answering ends of the cord circuits for con necting said cord circuits with calling lines, and apparatus for changing the electrical character of the cord circuits to cause them, when idle, to cooperate with the selective switching mechanism as if they were busy, to enable the said mechanism to pass the same into cooperation with an idle cord circuit that may be used, substantially as described.

12. A telephone exchange system includinga plurality of telephone lines provided with jacks and divided into groups, a plurality of cord circuits for each group of telephone lines also divided into groups and extending to cord connecting plugs at different sections of the switch-board, the connecting plugs of each group being distributed among the operators positions at each section, automatically operated selective switching mechanism, including traveling li-ne terminals and multipled cord contacts engaged by said terminals, said switching mechanism being associated with the telemechanism being phone linesand the answering ends of the cord circuits for connecting said cord circuits with calling lines, and apparatus for changing the electrical character of the cord circuits to cause them, when idle, to cooperate with the selective switching mechanism as if they were busy, to enable the said mechanism to pass the same into coopera tion with an idle cord circuit that may be used, substantially asdescribed.

13. A telephone exchange system including a plurality of telephone lines provided with jacks and divided into groups, a plurality of cord circuits for phone lines also divided into groups and extending to cord connecting plugs at different sections of the switch-board, automatically operated selective switching mechanism associated with the telephone lines and the answering ends of the cord circuits fo connecting said cord circuits with calling lines, apparatus for checking the operation of the selective switching mechanism and cord circuit apparatus governing the aforesaid apparatus to enable the selective switching mechanism to avoid busy cords, and apparatus for changing the electrical character of the cord circuits to cause them, when idle, to cooperate with the selective switching mechanism as if they were busy, to enable the said mechanism to pass the same into co operation with an idle cord circuit that may be used, substantially as described.

14. A telephone exchange system including a plurality of telephone lines provided with jacks and divided into groups, a plurality of cord circuits for each group of telephone lines also divided into groups and extending to cord connecting plugs at different sections of the switch-board, the connect-' ing plugs of each group being distributed among the operators positions at each section, automatically operated selective switching mechanism associated with the telephone lines and the the cord circuits for connecting said cord circuits with calling lines, apparatus for checking the operation of the selective switching mechanism and cord circuit apparatus governing the aforesaid apparatus to enable the selective switching mechanism to avoid bu'sy cords, and apparatus for changing the electrical character of the cord circuits to cause them; when idle, to -co operate with the selective switching mechanism as if they were busy, to enable the said mechanism to pass the same into cooperation with an idle cord circuit that may be used, substantially as described.

15. A telephone exchange system including a plurality of telephone lines provided with jacks and divided into groups, a plurality of cord circuits for each group of telephone lines also divided into groups and extending to cord connecting plugs at difi'ereach group of teleanswering ends of cut sections of the switch-board, automatically operated selective switching mechanism, including multipled cord contacts engaged by said terminals, said switching mechanism being associated with the telephone lines and the answering ends of the cord circuits for connecting said cord circuits with calling lines,-

apparatus for checking the operation of the selective switching mechanism and cord circuit apparatus governing the aforesaid apparatus to enable the selective switching mechanism to avoid busy cords, and apparatus for changing the electrical character of the cord circuits to cause them, when idle, to cooperate with the selective switghing mechanism as if they were busy, to enable the said mechanism to pass the same into cooperation with an idle cord circuit that may be used, substantially as described.

16. A telephone exchange system including a plurality of telephone lines provided with jacks and divided into groups, a plurality of cord circuits for each group of telephone lines also divided into groups and extending to cord connecting plugs at different sections of the switch-board, the connecting plugs of each group being distributed among the operators positions at each section, automatically operated selective switching mechanism, including traveling line terminals and multipled cord contacts engaged by said terminals, said switching mechanism being associated with the telephone lines and the answering ends of the cord circuits for connecting said cord circuits with calling lines, apparatus for checking the, operation of the selective switching mechanism and cord circuit apparatus governing the aforesaid apparatus to enable the selective switching mechanism to avoid busy cords, and apparatus for changing the electrical character of the cord circuits to cause them, when idle, to'cooperate with the selective sw'tching mechanism as it they were busy, to enable the said mechanism to pass the same into cooperation with an idle cord circuit that may be used, substantially as described.

17. A telephone exchange system including a plurality of telephone lines provided with jacks and divided into groups, a plurality of link circuits for each group of telephone lines also divided into groups and extending to link connecting plugs at different sections of the switch-board, automatically operated selective switching mechanism associated with the telephone lines and the answering ends of the link circuits for coniiecting said link circuits with calling lines, apparatus for changing the electrical character of the link circuits to cause them, when idle, to cooperate with the selective switching mechanism as if they were busy, to enable the said mechanism to pass traveling line terminals and the same into cooperation with an idle link circuit that may be used, additional link circuits equipped similarly to the aforesaid link circuits and extending between the board sections and the groups of telephone lines, and a'distributing agency by means of which said latter link circuits are completed, substantially as described.

18. A telephone exchange system including a plurality oi telephone lines provided with jacks and divided into groups, a plurality of phone lines also divided into groups and extending to cord connecting plugs at diiierent sections of the switch-board, the connecting plugs of each group being distributed among the operators positions at each section, automatically operated selective switching mechanism associated with the telephone lines and the answeringends of the cord circuits for connecting said cord circuits with calling lines, apparatus for changing the electrical character of the cord circuits to cause them, when idle, to cooperate with the selective switching mechanism as. if they were busy, to enable the said mechanism to pass the same into cooperation with an idle cord circuit that'may be used, additional cord circuits equipped similarly to the aforesaid cord circuits and extending between the board sections and the groups of telephone lines, and a distributing agency by means of which said latter cord ci pleted, substantially as described.

19. A telephone exchange system including aplurality of telephone lines provided with jacks and divided into groups, a plurality of cord circuits for each group 0 telephone lines also divided into groups an extending to cord connecting plugs at different sections of the switch-board, automatically operated selective switching mechanism, including traveling line terminals and multipled cord contacts engage by said terminals, said switching mechanism being associated with the telephone lines and the answering ends of the cord circuits for connecting said cord circuits with calling lines, apparatus for changing the electrical character of the cord circuits to cause them, when idle, to cooperate with the selective switching mechanism as if they were busy, to enable the said mechanism to pass the same into cooperation with an idle cord circuit that may be used, additional cord circuits equipped similarly to the aforesaid cord circuits and extending between the board sections and the groups of telephone lines, and a distributing agency by means of which said latter cord circuits are completed, substantially as described.

20. A telephone exchange system including a plurality of telephone lines provided with jacks and divided int-c groups, a plurality of cord circuits for each group of telecuits are coin-- cord circuits for each group of telephone lines also divided into groups and exthe answering ends of the tending to cord connecting plugs at different sections of the switch-board, the connecting plugs of each group being distributed among the operators positions at each section, auto'- matically operated selective switching mechanism, including traveling line terminals and multipled cord contacts engaged by said terminals, said switching mechanism being associated with the telephone lines and the answering ends of the cord circuits for connecting said cord circuits with calling lines, apparatus for changing the electrical character of the cord circuits to cause them, when idle, to cooperate with the selective switching mechanism as if they were busy, to enable the said mechanism to pass the same into cooperation with an idle cord circuit that may be used, additional cord circuits equipped similarly to the aforesaid cord circuits and extending between the board sections and the groups of telephone lines, and a distributing agency by means of which said latter cord circuits are completed, substantially as describe 21. A telephone exchange system including a plurality of telephone lines provided with jacks and divided into groups, a plurality of cord circuits for each group ,of telephone lines also divided into groups and extending to cord connecting plugs at different sections of the switch-board, automatically operated selective switching mechanism associated with the telephone lines and cord circuits for connecting said cord circuitswith calling lines, apparatus for checking the operation of the selective switching mechanism and cord circuit apparatus governing the aforesaid apparatus to enable the selective switch ing mechanism to avoid busy cords, apparatus-for changing the electrical character of the cord circuits-to cause them, when idle, to cooperate with the selective switching mechanism as if they were busy, to enable the said mechanism to cooperation with an idle cord circuit that may be used, additional cord circuits equipped similarly to the aforesaid cord circuits and extending between the board sectially as described. v

22. A telephone exchange system including a plurality of telephone lines provided with jacks and divided into groups, rality of cord circuits phone lines also divided into groups and extendlng to cord connecting plugs at different sections of the switch-board, the connecting plugs of each group being distributed among the operators positions at each section, automatically operated selective switching mechanism assoclated with the telephone pass the same into lines and the answering ends of the cord circuits for connecting said cord circuits with calling lines, apparatus for checking the operation of the selective switching mechanism and cord circuit apparatus governing the aforesaid apparatus to enable the selective switching mechanism to avoid busy cords, apparatus for changing the electrical character of the cord circuits 1 when idle, to cooperate with the selective switching mechanism as if they were busy, to enable the said mechanism to pass the same into cooperation with an idlecord circuit that may be used.

23. A telephone exchange'system includ ing a plurality of telephone lines provided with jacks and divided into groups, a plurality of cord circuits for each group of telephone lines also divided into groups and extending to cord connecting plugs at different sections of the switch-board, automatically operated selective switching mechanism, including traveling line terminals and multipled cord contacts engaged by said terminals, said switching mechanism being associated with the telephone lines and the answering ends of the cord circuits for connecting said cord circuits with calling lines, apparatus for checking the operation of the selective switching mechanism and cord circuit apparatus governing the aforesaid apparatus to enable the selective switching mechanism to avoid busy cords, apparatus for changing the electrical character of the cord circuits to cause them, when idle, to cooperate with the selective switching mechanism as if they were busy, to enable the said mechanism to pass the same into cooperation with an idle cord circuit that may be used, additional cord circuits equipped similarly to the aforesaid cord circuits and extending between the board sections and the groups of telephone lines, and a by means of which said are completed, substantially as described. v

24. A telephone exchange system includ ing a plurality of telephone lines provided with jacks and divided into groups, a plurality of cord circuits for each group. of telephone lines also divided into groups and extending to cord connecting plugs at diiferent sections of the switch-board, the connecting plugs of each group being distributed among the operators positions at each section, automatically operated selective switch ing mechanism, including traveling line terminals and multipled cord contacts engaged by said terminals, said switching mechanism being associated with the telephone lines and the answering ends of the cord circuits for connecting said cord circuits with calling lines, apparatus for checking the operation of the selective switching mechanism and cord circuit apparatus governing the aforesaid apparatus to enable to cause them,

, cuits for each the telephone lines and the arness the selective switching mechanism to avoid busy cords, apparatus for changing the electrical charactenot the cord circuits to cause them,

tive switching mechanism'as if they were busy, to enable the said mechanism to pass the same into cooperation with an idle cord circuit that may be used, additional cord circuits equipped similarly to the aforesaid cord circuits and extending between the board sections and the groups of telephone lines, and a distributing agency by means 0 which said latter cord circuits are completed, substantially as described.

25. A multiple switch-board telephone exchange system including a plurality of telephone lines divided into groups pled to different sections of the multiple switch-board and provided at each of such sections with a jack,

group of telephone lines also divided into groups and extending to link connecting plugs at different sections of the switch-board, automatically operated selective switching answering ends for connecting said link of the link circuits circuits withcalling lines, and apparatus for switching mechanism as if they were changing the electrical character 0 the link circuits to cause them, when idle, to cooperate with the selective switching mechanism as if they were busy, to enable the said mechanism to pass the same into cooperation with an idle link circuit that may be used, substantially as described.

26. A multiple switch-board telephone exchange system including a plurality of tele- )llOIlQ lines divided into groups and multipled to different sections oi the multiple switch-board and provided at each of such sections with a jack, a plurality of cord circuits for each group of telephone lines also divided into groups and extending to corr connecting plugs at different sections of the switch-board, the connecting plugs of each group being distributed among the operators positions at each section, automatically operated selective switching mechanism associated with the telephone lines'and the answering ends of the cord circuits for connecting said cord circuits with calling lines, and apparatus for changing the electri 'al character of the cord circuits to cause them,

the selective busy, to enable the said mechanism to pass the same into cooperation with an idle cord circuit that may be used, substantially as described. M 27. A multiple switch-board telephone exchange system including a plurality of telephone lines divided into groups and multipled to different f the multiple switch-board and provided at each of such sections with a ack, a plurality of cord cirwhen idle, to cooperate with when idle, to cooperate with the seleccord circuits a plurality of link cir-.

mechanism associated withcuits for each group of telephone lines also divided into groups and extending to cord connecting plugs at diiierent sections ot the switch-board, automatically operated selective switching mechanism, including traveling line terminals and multipled cord contacts engaged by said terminals, said switching mechanismbeing associated with the telephone lines and the answering ends of the for connecting said cord circuits with calling lines, and apparatus for changing the electrical character of the cord circuits to cause them, when idle, to cooperate with the selective switching mechanism asif they were busy, to enable the said mechanism to pass the same into cooperation with an idle cord circuit that may be used, substantially as described.

28. A- multiple switch-board telephone exchange system including a plurality of telephone lines divided into groups and multipled to different sections otthe multiple switch-board and provided at each of such sections with a jack, a plurality of cord circuits for each group of telephone lines also divided into groups and extending to core connecting plugs at different sections of the switch-board, the connecting plugs of each group being distributed among the operators positions at each section, automatically operated selective switching mechanism, including traveling line terminals and multipled cord contacts engaged by said terminals, said switching mechanism being associated with the telephone lines and the answering ends of the cord circuits for coiinecting said cord circuits with calling lines, and apparatus for changing the electrica character of the cord circuits to cause them, when idle, to cooperate with the selective switching mechanism as if they were usy, to enable the said mechanism to pass the same into cooperation with an idle cord circuit that may be used, substantially as described. v

29. A multiple switchboard telephone eX- change system including a plurality of telephone lines divided into groups and multi pled to dil'lerent sections of the multiple switch-board and provided at each of such sections with a jack, a plurality of cord circuits for each group of telephone lines also divided into groups and extending to CO1 connecting plugs at different sections of the switch-board, automatically operated seleccircuits to cause them, when idle, to cooperate with the selective switching mechanism as if they were busy, to enable the said mechanism to pass the same into cooperation with an idle cord circuit that may be used, substantially .as described.

80. A multiple switch-board telephone eX- change system including a plurality of telephone lines divided into groups and multipled to different sections of the multiple switch-board and provided at each of such sections with a jack, a plurality of cord circuits for each group of telephone lines also divided into groups and extending to cord connecting plugs at switch-board, the connecting plugs of each group being distributed among the operators positions at each section, automatically operated selective switching mechanism associated with the telephone lines and the answering ends of the cord circuits for connecting said cord circuits with calling lines, apparatus for checking the operation of the selective switching mechanism and cord circuit apparatus governing the aforesaid apparatus to enable the selective switching mechanism to avoid busy cords, and apparatus for changing the electrical character of the cord circuits to cause them, when idle, to cooperate with the selective switching mechanism as if they were busy, to enable the said mechanism to pass the same into cooperation with an idle cord circuit that may be used, substantially as described.

31. A multiple switch-board telephone exchange system including a plurality of telephone lines divided into groups and multipled to difierent sections of the multiple switch-board and provided at each of such sections with a jack, a plurality of corl circuits for each group of telephone lines also divided into groups and extending to cord connecting plugs at different sections of the switch-board, automatically operated selective switching mechanism, including traveling line terminals and multipled cord con tacts engaged by said terminals, said switching mechanism being associated with the telephone lines and the answering ends of. the cord circuits for connecting said cord circuits with calling lines, apparatus for checking the operation of the selective switching mechanism and cord circuit apparatus governing the aforesaid apparatus to enable the selective switching mechanism to avoid busy cords, and apparatus for changing the electrical character of the cord circuits to cause them, when idle, to cooperate with the selective switching mechanism,

as if they. were busy, to enable mechanism to pass the same into cooperation with an idle cord circuit that may be used, substantially as described.

32. A multiple switch-board telephone exchange system including a plurality of telediflferent sections of the Y enses phone lines divided into groups and multipled to different sections of the multiple switch-board and provided at each of such sections with a jack, a plurality of cord circuits for each group of telephone lines also divided into groups and extending to cord connecting plugs at different sections of the switch-board, the connecting plugs of each group being distributed among the operators positions at each section, automatically operated selective switching mechanism, including traveling line terminals and multipled cord contacts engaged by said terminals, nism being associated with the telephone lines and the answering ends of the cord circuits for connecting said cord circuits with calling lines, apparatus for checking the operation of the selective switching mechanism and cord circuit apparatus governing the aforesaid apparatus to enable the selective switching mechanism to avoid busy cords, and apparatus for changing the electrical character of the cord circuits to cause them, when idle, to cooperate with the selective switching mechanism as if they were busy, to enable the said mechanism to pass thfe'same into cooperation with an idle cord circuit that may be used, substan tially as described.

33. A multiple switch-board telephone exchange system including a plurality of telephone lines divided into groups andmultisections with a jack, circuits for each group of telephone lines also divided into groups and extending to cord connecting plugs at different sections a plurality of cord provided at each of such sections with a jack,

cuits for each group of telephone lines also said switching mecha a plurality of cord cirdivided into groups and extending to cord sections with a jack,

connecting plugs at different sections of the switch-board, the connecting plugs of each group being distributed among the operators positions at each section, automatically operated selective switching mechanism associated with the telephone lines and t answering ends of the cord circuits for connecting said cord circuits with calling lines, apparatus for changing the electrical character of the cord circuits to cause them, when idle, to cooperate with the selective switching mechanism as if they were busy, to enable the said mechanism to pass the same into cooperation with an idle cord circuit'thatunay be used, additional cord circu ts equippedsimilarly to the aforesaid cord circuits and extending between the board sections and the groups of telephone lines, and a distributing agency by means of which said latter cord circuits are completed, substantially as described.

85. A multiple switch-board telephone exchange system including a plurality of telephone lines divided into groups and multipled to different sections of the multiple switch-board and provided at each of such a plurality of cord circuits for each group ottelephone lines also divided into groups and extending to -ord connecting plugs at different sections of the switch-board, automatically operated selective switching mechanism, including traveling line terminals and multipled cord contacts engaged by said terminals, said switching mechanism being associated with the telephone lines and the answering ends of the cord circuits for connecting said cord circuits with calling lines, apparatus for changing circuits to cause them, when idle, to cooperate with the selective. switching mechanism as if they were busy, to enable the said mechanism to pass the same into cooperation with an idle cord circuit that may be used, additional cord circuits equipped similarly to the aforesaid cord circuits'and extendingbetwcen the board sections and the groups of telephone lines, and a distributing agency by means of which said latter cord circuits are completed, substantially as described. a

36. A multiple switch-board telephone exchange system including a plurality of telephone lines divided into groups and multipled to different sections of the multiple switch-board and provided at each of such sections with a jack, a plurality of cord circuits for each group also divided into groups and extending to cord connecting plugs at different sections of the switch-board, the connecting plugs of each groupbeing distributed among the operators positions at each section, automatically operated selective switching mechanism, including traveling line termthe electrical characterof the cord of telephone lines.

lective switching mechanism as it they were busy, to enable the said mechanism to pass the same into cooperation with an idle cord circuit that may be used, additional cord circuits equipped similarly to the aforesaid cord circuits and extending between the board sections and the groups of telephone lines, and a distributing agency by means of which said latter cord circuits are completed, substantially as described.

37. A multiple switch-board telephone exchange system including a plurality of telephone lines divided into groups and multipled to diilerent sections of the multiple switch-board and provided sections with a jack, a plurality of cord circuits for each group of telephone lines also divided into groups and extending to'cord connecting plugs at diiierent sections of the switch-board, automatically operated selective switching mechanism associated with the telephone lines and the answering ends of the cord circuits for connecting said cord circuits with calling lines, apparatus for checking the operation of the selective switching mechanism and cord circuit a ppa 'atus governing the aforesaid apparatus to enable the selective switching mechanism to avoid busy cords, apparatus for changing the electrical character of the cord circuits to cause them, when idle, to cooperatewith the selec tive switching mechanism as if they were at each of such busy, to enable the said mechanism to pass the same into cooperation with an idle cord circuit that may be used, additional cord circuits equipped similarly to the aforesaid cord circuits and extending between the board sections and the groups of telephone lines, and a distributing agency by means of which said latter cord circuits are completed, substantially as described.

38. A multiple switch-board telephone exchange system including a plurality of telephone lines divided into groups and multipled to different sections of the multiple switch-board and. provided at each of such sections with a jack, a plurality of cord circuits for eachgroup of telephone lines also divided into groups and extending 'to cord connecting plugs at different sections of the switch-board, the connecting plugs of each group being distributed among the operators positions at each section, automatically operated selective switch ng mechanism. associ ted with the telephone lines and the answering ends of the cord circuits for ccinnecting said cord circuits 

